Apparatus for determining conditions within a gun barrel



3 R m m 7 O, Kw P 2 H Y R N E m H m mt. Rmmm EGB Rm m c Hm .Emd H m mmm s w m A Aug. 1, 1950 ATTORNEY Patented Aug. 1, 1950 APPARATUS FOR DETERMINING CONDI- TIONS WITHIN A GUN BARREL Henry H. Porter, Chicago, Ill., assignor to the United States of America as represented by the Secretary of the Navy Application August 10, 1943, Serial No. 498.108

16 Claims.

This invention relates to indicating systems for use in determining the conduct of a projectile in a gun barrel. More particularly, the invention has reference to a novel system of this character comprising a projectile having means disposed in a gun barrel and projecting from the muzzle thereof for transmitting information concerning the conduct of the projectile while passing through the barrel.

One object of the invention resides in the provision of a novel system for indicating the conduct of a projectile passing through a gun barrel,

which comprises a wire connected to the projectile and designed to extend through the barrel and out the muzzle of the gun for carrying a signal from the projectile when the latter is fired from the gun.

Another object of the invention is to provide a system of the character described in which the projectile is provided with an antenna or wire electrically coupled to a signal producing means in the projectile for transmitting a signal along the gun bore to operate an oscilloscope, or the like, through a suitable receiver. In accordance with one form of the invention, the projectile contains a source of electrical energy andan oscillating circuit designed to be energized by the source. The antenna or wire is coupled to the oscillating circuit in the projectile and extends along the bore of the gun and out of the muzzle, preferably from the nose of the projectile. The antenna or wire is held out of contact with the gun, as by means of a suitable support on the muzzle, and when the gun is fired, the antenna or wire is collected in the nose portion of the projectile as it moves through the barrel.

Another object of the invention resides in the provision of a novel projectile having apparatus for use in determining the conduct of the projectile in the bore of a gun. In one form of the invention, the projectile includes an insulating member in the nose portion of the projectile having a recess from which an antenna extends through the bore of the gun, whereby the antenna is collected in the recess as the projectile moves through the gun barrel. The recess has a metal bottom to provide continuous contact with the antenna during collection thereof and to provide a coupling of constant capacitance between the antenna and the radiating means. Within the projectile to the rear of the antenna collector is a block which is insulated from the projectile body and carries the parts of the oscillating circuit. The oscillator parts, is desired, may be embedded in the block so that they are adequately supported and protected against damage do to the shock in firing the projectile in the gun. The source of electricity for energizing the oscillating circuit is preferably included in another block insulated from the casing and mounted inthe projectile adjacent the block containing the oscillating circuit, the two blocks havingreleasable electrical connections between them to supply electricity to the oscillator and permit ready assembly and disassembly of the projectile.

The specific object of the invention is to provide a process and means for observing and recording the impulse vibrations of a projectile, due

to firing of the gun, while said projectile is still within the gun barrel.

Other objects and many of the attendant advantages of this invention will be appreciated readily as the same becomes understood by reference to the following detailed description, when considered in connection with the accompanying drawings, wherein:

Fig. 1 is a diagrammatic view of one form of the new indicating system;

Fig. 2 is an enlarged detail ;view of the muzzle portion of the gun shown in Fig. 1;

Fig. 3 is a longitudinal sectional view of the muzzle portion of the gun showing the projectile as it moves through the barrel;

Fig. 4 is a wiring diagram of the oscillating circuit, and

Fig. 5 is an enlarged longitudinal sectional view of the nose portion of the projectile.

Referring to the drawing, the system there shown comprises a projectile having a casing ill of any suitable form, a rotating band I I near the tail end of the projectile, and a nose portion 12 which may be secured to the casing by the usual threaded connection. The projectile is loaded in a gun I3 having a bore l3a provided with the usual rifiing (not shown), the main body of the projectile being disposed in the bore with the rotating band I l in the gun chamber to the rear of the rifiing. As shown, the projectile is of the fixed ammunition type and is held at its tail end in a cartridge case M'containing a firing charge, although it will be understood that the firing charge may be contained in bags in the gun chamber so as to eliminate the cartridge case. A breech mechanism I5 is mounted on the gun at its rear end and includes a suitable device I511 for exploding the firing charge in the cartridge case.

In the nose portion of the projectile is a radio transmitter I! having an oscillating circuit, to

be described in detail presently, and an antenna Ill electrically coupled to the oscillating circuit. The antenna, which may be coiled, extends from the projectile through the bore of the gun to a support I9 at the muzzle. The support comprises an insulating ring l9a which fits over the muzzle portion of the gun and carriesa 'support* ing strand IQb made of silk or other insulating material. The strand extends diametrically across the ring and is secured at one end by a knot I90, the opposite end of the strand being held in a notch 9d in the ring. Intermediate :its ends, the strand l9b is connected to the antenna l8, as by means of a knot the, so as to hold the antenna out of contact with the gun barrel. From the strand l9b a short length of the antenna hangs downwardly fromthegun-"muz'zle.

The electromagnetic waves radiated from the antenna it are received by a radio receiver 21 which is tuned, as by means of a dial 21a, to the frequency of the estimatin circuit in the trans mi't te'r ll. "rise-output end or the receiver 21 is connected through wires "22 to a "suitable indica torjsuch-as a cathoderay oscilloscope 23. Preferably, a camera 26 is provided adjacent the os-- cille'scope for recording the readings thereof. If desire"cl, a suitable recorder (not shown) may beoperated by the output from "the receiver 11 "Thetra'ns itter l l-may-be of any desired form. sho'wn in "'4, it coinprise'san electron discharge tube having a plate 26, a filament 21 and a grid E8. one side of the filament 2 1 is connected through a switch 29 and 'a releasable plug-and-socli'et connection 30 to a terminal 31 at the negative side of an A battery E2. The other side of the filament 21 is-"connected through areleasable'plugand socliet connections to the website-side of battery -32. The negative side of a B battery 3% is connected to the terminal 3|, and the positive 'si'de 'o'f' thaB battery'is-connec'te'd through arleasab le qsiu'g 'and-'socket connection to a resistor 36. resistor is connected through a radio fi e'quency choke *coil Bl and a capacitor 38 to the "grid 2 B of 'thetub'e. A gridbias res'is'tor"39 is-coiine'otedb'etween the filament and grid circuits. The'plate -26 of thetube is connected "to one terminal (if a "tank coil 'dll, the

opposite terminal of which isconnectedbetween the capacitor 38 andthechcke coil '37.

The transmitter is contained i'n'th'e projectile in two sections, one of which comprisesa memher 42 '-made of insulating material, such as Lucite, mounted at the nose or "the projectile. In the no'seend'of the nie'mberfl is agen'erally cup-shaped recess $3, the "open 'end of which faces the 'muzzle'of the gun. The'side walls'of recess 43 converge from the-nose *endof thememher to a restricted portion M "and then diverge to the bottom of 'the recess. A terminal "screw 45 isthreaded in the bottom of *the recess M2 for-connection to the antenna [8. In the rear end of the member 42 "is "a "generally cup-shaped recess lli having its'op'enend facingto therear, iherecesses l3'a nd45 being separated by a'partition ll. Fitted closely'inthe recess lfi'is a block 48 made of an insulating compound, such "as Lucite, in which the lpart'soffthe "oscillating "circuit areembedded If desiredthe block "48 may be fr'noldedaround thepa'rts ofthe oscillating circuit, includingthetube, the resistors 36 and 39, the apacitor taandthe coins "Brand 4! Also, oneelem'erit of "each "of the" plugand-so'cket connections 3D, 33 and 35 is embedded in the block 418. A metal plate -4'9 is 1 held against *the bottom (if recess 43 adjacent the tank "coil 41] and has 4 the screw 45 threaded into it, the plate serving as a coupling of substantially constant capacitance between the oscillator and the antenna. The plate 19 also serves as a contact means for maintaining continuous electrical contact with the antenna during collection thereof, even though the inner end of "the antenna should become detached from screw 45, The switch 29 in the filament circuit may conveniently take the form of a contact screw 29a threaded in the sidewall of member 42 and engageable with a coacting contact 28b adjacent its inner end. Normally, the screw 29a is withdrawn out of {enga ement with contact 2912 so as to open- *the filament circuit.

"The other section of the transmitter comprises block 56 of insulating material disposed in a recess 5| in the metal nose portion [2 of the projectile. The block 50 has mounted in it the A and B batteries 32 and 34 and the other elements of "the -'plug-and-'socl et connections 30, 33 {and 35.

The member 12 maybe *connected to the nose portion l E o'f'th'e projectile in any suitable man n'er. AsshoWn, the member '42 is provided with a ring "52!;xtndlng around the outside of the member at "its rear end over an annulus 53 for securing the ring and member against relative axial movement. The ring projects rearwardly from the member 4-2 and its projecting portion is provided with internal threads 5i iwhich mate with similar threads on the nose 12. Thus, in the assembly or the projectile, the block 5G is inserted in the nose recess 551, the member "42 is placed over-the r'iose-end of block at with the plug and-soc'ket connections 30, 33 and 35 engaged, and the ring 52 is screwed ov e'r threads-on the nose I2 so'as'to clamp the parts fir'm'l'y together.

The oscilloscope "'23 is provided with a sweep circuit including a pair of 'tern'iina'ls connected with a source 55 of electricity and a sWitch 55 associated with the "firing device I5a. Thesw' itch 56 and the source '55 cooperate to produce a trigger circuit for initiating an impulse in the sweep circuit 'in the oscilloscope "23 when the gun is "fired. The receiver 2| is provided with an antenna (not shown) for receiving waves radiated from 'the antenna la. The output-of the receiver is connected with the vertical deflection terminals of the oscilloscope by the wires 22 for modulating the sweep voltage initiated by the trigger circuit previously described.

In operation, the switch 28 in the filament circuit'of oscillator'tub'e 25 is closed by tightening screw 28a, and the projectile is loaded into the gun for firing, with the antenna l8 extendingout throughthebore, as shown in Fig. 1. It

will be understood that whenswitc'hzfl is closed, the'oscillating circuit is energized'by the "source of electricity'in block 55],so that electromagnetic Wavesare emitted from the antenna l3. The radio-receiver M is tuned to the frequency of the'wave's emitted from the oscillator; the shutter of the oscilloscope camera 26 is opened, andfif jectile, 'The outer portion of theside walls 'o'f oscillator IT, with the result that the signals received by the receiver 2! are correspondingly aifected, as indicated by the oscilloscope or the sound recorder. It should be understood that the emitted signal is modulated by suitable means, such as a switch 5'! which is opened and closed by any suitable means and shown diagrammatically in Figure 4, a crystal, a flexible capacitor, or other electrical component. It should be understood that the switch 5'! can be anyone of a number of well known intermittently operable types; for example said switch can be of the thermal element type, such as has well known use with blinker systems. The sole purpose of the switch is to provide modulation so that the signal emitted from the transmitter may be easily identified. Other forms of modulation can be used, if space therefor is available, for example, a small audio oscillator could be employed. The inventor has found in experiments carried out with the new system that signals from the transmitter I! may be heard in the receiver 2| while the projectile is in the gun barrel, and that valuable data concerning the conduct of the projectile in the gun barrel can be obtained from the signals. More specifically, data obtained from the oscilloscope 23 and from a sound recording device associated with the receiver show that oscillation inthe projectile does not cease until the projectile is well out of the gun barrel. Also, such data provide a basis for determining the vibration of the tube filament 2'! in the gun barrel, and also provide information in'rega'rd to acceleration of the projectile throughout its movement in the barrel. Additionally, the system may be used to obtain a record of the impulse vibrations in the gun.

The new system may be assembled readily and is easy to operate. Since the component parts of the transmitter ll are embedded in the insulating blocks 48 and 5! they are capable of withstanding the heavy shocks incident to firing the projectile in the gun. Also, by mounting the parts of the transmitter I! in two separate units 48 and 50 and providing detachable electrical connections 30, 33 and 35 between the units, the projectile may be readily assembled and di' assembled.

The provision of an antenna positioned in a gun barrel to project therefrom for the purpose of emitting a signal generated in a projectile in the barrel, is merely one possible arrangement. Although the transmitter I! has been disclosed in the form of an oscillator unit, it will be understood that other means may be employed for producing a signal or impulse to be received by the receiver 2|. Also, if desired, the parts of the transmitter I? may be mounted in a single unit instead of the two detachable units 48 and 50, or they may be mounted in three or more units designed to be received in the projectile.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. An indicating apparatus for use in determining the conduct of a projectile in a gun barrel, which comprises a radio transmitter in the projectile, an antenna electrically coupled to the transmitter and extending from the projectile along the bore of the gun, and a receiver remote from the projectile and tuned to the frequency of the transmitter for receiving signals emitted from the antenna.

2. In combination, a projectile to be loaded into a gun for firing, a radio transmitter in the projectile, means electrically coupled with the transmitted for radiating energy from adjacent the muzzle of the gun, and a radio receiver tuned to the frequency of the transmitter for receiving signals from said radiating means.

3. An apparatus for determining the conduct of a projectile in a gun barrel, which comprises an electrical oscillator unit in the projectile, a

source of electrical energy in the projectile forenergizing the oscillator unit, means electrically coupled with the oscillator unit and extending along the bore of the gun for radiating energy from adjacent the muzzle of the gun, and a radio receiver tuned to the frequency of the oscillator unit for receiving signals from said radiating means during the passage of the proectile through the barrel.

4. An apparatus for determining the conduct of aprojectile in a gun barrel, which comprises an oscillator unit in the projectile, a source of electrical energy in the projectile for energizing the oscillator unit, a manually operable switch in the projectile for electrically connecting said source to the oscillator unit, means electrically coupled with the oscillator unit and extending along the bore of the gun for radiating energy from adjacent the muzzle of the gun, and a radio receiver tuned to the frequency of the oscillator unit for receiving signals from said radiating means as the projectile moves along the gun barrel.

5. In combination, a projectile to be loadedv into a gun for firing, a radio transmitter in the projectile, an antenna electrically coupled to the transmitter and extending from the projectile along the gun barrel for radiating energy from adjacent the muzzle of the gun, a radio receiver tuned to the frequency of the transmitter, and an oscilloscope electrically connected to the output end of the receiver.

6. In combination, a projectile to be loaded into a gun for firing, a radio transmitter in the projectile, an antenna electrically coupled to the transmitter and extending from the projectile along the bore of the gun for radiating energy from adjacent the muzzle of the gun, a radio receiver tuned to the frequency of the transmitter, and means for indicating the output 7 projectile, anantenna electrically rconpled with the transm'itter .and extending .irom the projectile along the bore \of the :gun for :radiating energy from adjacent the muzzle 10f :the gun, *a collector unit on the nose portion of :the :pro jectile florrece'iving the antenna as the projectile moves through the gun barrel, and a :radio :re- CBiVeI tuned to the frequency of the transmitter for receiving signals -from the antenna.

9. :In combination, -a projectile to be :loaded into a .gun :for firing, ,a transmitter in the .pro .ject'ile, .an :antenna electrically coupled to .tne transmitter and extending along the bore-0f the tier .radiating energy from adjacent the muzzle of the 1gun,:insulating means mounted :on

themuzzle of thergun iforsupporting the antenna to miaintain the antenna out of contact with the gun,;and a'zreceiyer tuned to the -:fr.equency oi the-transmitter Ffor receiving signals from .the

antenna.

:10. :Inua projectile, a radio transmitter for use in--:determining "the iconduct of the :projectile in a gunbarrel, which comprises electrical :operat ingielemen'ts, electrlcalconnections between said elements, insulating means in which said ;ele-

ments and connections "are embedded, means for "securing :said insulating means 'to the projectile'body, and, an antenna electrically coupled tosaidoper-ating elements and extending from the mose of the projectile.

11. In a projectile, a radio tr,ansmitter:for-use in determining the conduct :of the projectile in a gun barrel, which comprises .an .electrical oscillator ;unit including operating elements and electrical {connections between the elements, an insulating block :in which said elements and iconnections are embedded, a source of electrical energy, a second insulating block in Whichvsaid source is embedded, releasable electrical connections between :said blocks :for conducting currenttfromsthe source'to "saidiirst electrical connections, and means for securing said :blocks to trically coupled to .theoscillator and having one 5 end disposed in said'recess in the nose end of the member, whereby the antenna is adapted to be collected in said recess was the projectile moves through the gun barrel.

In aiprojectileia radio transmitter iorzuse in :determining the conduct .of the projectile :in a gun barrel, which comprises a member at the nose portion of the projectile insulated from the v projectile body, -.insulating,means in saidmember, .an oscillator unit embedded ,in said insulating :means and including an oscillator tube .having :a filament, a manual switch in the side wall of .said member for closing the energizing circuit of :said filament, means for securing said member to the 1oodyof the projectile, .and means in 'theprojectile body-ior energizing the oscillator unit.

.14. In -a projectilaqaradio transmitter for use in :determining the conduct. of the projectile in a :gun barrel, which comprises :a member at the nose of the projectile insulated from the projectile bcdy, insulating materialin :said'membenanoscillatorunit embedded in said material,

releasable :means for connecting saiohrnemher to the projectile body, ;an insulating block disposed in a :recessin the :nose portion 'of. :the projectile body .to the -rear of :said first block,- energizing means embedded :in said block, and releasable electrical connections between said blocks tier energizing meansv producing means in the projectile, :a wire coupled to'saidimeans and extending from the projectile along the hereof the gun, and a receiver remote from the projectile :ior receiving from said means a-signal transmitted along the wire.

- v:16. *In combination .a projectile .to be loaded into :and fired from 'a gun, an indicating apparatus :for determining the conduct of the ;projectile in the. gun barrel, which ,comprises means in the projectile "for producing :an electricalsignal, a'wire-electrically coupled to said -means and extendingxfrorn the projectile .along the ,gunbore and out of .the .muzzle, and a receiver remote fromtheprojectile for receiving thersignal from said wire.

HENRY H. PORTER.

REFERENCES errnn The following references are of :record in the file "of this patent:

' UNITED STATES PATENTS Number :Name Date 2,018,080 Martienssen .Oct.22, 19.35 2,293,949 Potter Aug. 25,1942 2,412,575 .Frosch Dec. 1?, 19%, 

